Archive for March, 2017

Building a Double Bass: The Ribs and Linings–Part One

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Bending and Installing Bass Ribs and Linings: Part 1

Gamba-corners versus Violin-corners

When I built my first bass, ten years ago, I built a bass rib bending “iron” of heavy aluminum pipe, and it worked acceptably for that bass, primarily because it was a “gamba-cornered” bass:

my first bass

Gamba-cornered bass: no recurve at the corners.

The gamba-cornered basses derive their name from their earlier predecessors, the viols. (Some people still refer to them as “bass viols”.)  The violas da gamba were a medium-sized viol, intended to be played in a sitting position, gripped between the knees, like a cello without an end-pin. Their corners had no recurve, so the basses with similarly shaped corners are called “gamba-cornered.”

But this bass, in addition to having a removeable neck, will be a “violin-cornered” bass, with sharp recurves at each corner. And, as it turned out, the old bending iron just wasn’t going to work. So I improvised by clamping a piece of 4″ ABS pipe to the workbench, draping a wet rag over the rib in progress, and “pressing” it with a clothes-iron. Surprisingly, it actually worked, just not all that well. I could get a rib flexible and roughly bent the way I hoped, but then had to quickly clamp the floppy rib into the mold and let it cool and dry there, and regain some rigidity.

Again; it actually worked… just not very well. It was a very frustrating process, and clumsy, much as if I had never built a bass before. I can tell that, before I build another bass, I need to build a better bending iron…and maybe streamline my mold a bit, as well– this one is a real tank, and inconvenient to use, as I did not use good foresight regarding where clamps would fit, so as to actually use the mold. (sigh…)

So, when I last posted photos (16 months ago…things have been busy) I had the mold prepared and the ribs ready for bending.

Bass mold with blocks installed and shaped

Bass mold with blocks installed and shaped. The mold will be removed, leaving only the blocks as part of the finisnhed Bass.

 

Bass ribs ready for bending.

Bass ribs ready for bending. The blocks were not shaped yet, in this picture. I ended up removing that neck block and replacing it with Spruce.

 

Bending and Installing the Ribs and Linings:

I always install the center bout ribs first–usually called the c-bout ribs. When the glue has dried on the c-bout ribs, they can be trimmed to match the outer curve of teh corner blocks, and the upper and lower ribs can be installed.

The C-bout ribs have been installed

The C-bout ribs have been installed and trimmed. I used salvaged ABS pipe for clampling cauls, and any sort of clamp I could lay hands on.

 

I really will have to improve my clamping arrangement  before building another bass. Probably will have to make major improvements on the mold, too.  I bend the upper ribs one section at a time, and clamped them to the mold to cool and dry, before making the next bend:

Beginning to form the upper bass-side rib.

Beginning to form the upper bass-side rib.

 

Bass side upper rib fully clamped

Bass side upper rib fully clamped.

 

Clamping nightmare.

Clamping nightmare.

 

More nightmares!

More nightmares! Those pipes tended to roll, throwing off the clamps. (sigh…)

 

And still more nightmares!

And still more nightmares! those sloping surfaces encouraged the clamps to slide off.

 

But finally, things began to shape up, one step at a time:

Both upper ribs in place

Once both upper ribs are in place it begins to look roughly like a bass.

 

Upper and C-bout ribs installed

Upper and C-bout ribs installed and trimmed. The bass is clamped to a table-top, so it looks huge, but it is only about 42″ tall.

So, the next step is the lower ribs; but I was uncomfortable handling the mold with the unprotected ribs, so I will install the upper and center linings before attempting to turn the mold over so I can install the lower ribs. The linings stiffen the edges of the ribs, as well as tripling the gluing surface presented to the front and back plates.

I installed the upper linings before trying to up-end the bass and install the lower ribs and linings:

Lining installation

The linings begin as straight strips of weeping willow, as shown. I bend and trim them to fit, then attach with hot hide glue.

 

Bass side linings complete. Treble side glued and clamped.

I only have sufficient clamps to attach one side at a time. You can see that I have already installed the bass side linings.

 

Back with no linings, yet

No linings at all on the back side, yet…that will be the next step. See how thin the ribs really are!

 

Upper and center linings completed on front side.

Upper and center linings completed on front side.

 

That is all I am going to post for now…the lower ribs and linings are next, but I have to create a fixture that will allow me to turn the bass to a variety of angles in order to work on it. I think I have a plan figured out: we will see how it turns out.

Meanwhile, another project has arrived on my doorstep. A lady sent me a cello begun by her dad, but which was still incomplete when he passed away 9 years ago. My assignment: resurrect that dream-cello! It will have to wait until May 1st, I think, but I am anxious to get started on it. It is made of beautiful bird’s-eye maple and what seems to be Red Spruce. I hope it turns out to be a great cello. Looking forward to the challenge. 🙂

Thanks for looking.

 

 

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3/4-Size Violin Completion

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Completed the 3/4-Size Violin!

I had a number of other projects going, so I neglected to maintain the website presence…the only post lately has been of another violin resurrection. But…I hope to change that.

The last post was of the neck-set on the 3/4 violin. It looked like this– but the back plate was not made, yet. Most makers complete the entire corpus, then set the neck. I complete the rib garland and the front plate, then set the neck while the inside mold is still in place. This allows me to get the neck-set perfect, and to level the back of the garland, including the back of the neck-heel, before making the plate. When I install the plate, it fits perfectly, only requiring the final trimming of the heel and button together, to establish the optimum height in the center of the curve of the heel.

Neck-set side view

Neck-set side view

Completing the Back Plate

So, the next thing was to trace the back plate, and complete it:

Corpus with back plate blank

Corpus with back plate blank

 

Beginning to carve the back archings

Beginning to carve the back archings. There is a long way to go!

 

Once the arching is complete, I cut the purfling slot

Once the arching is complete, I cut the purfling slot

 

 install the purfling, dry

Then I install the purfling, dry, to make sure everything fits correctly. That strip of aluminum is my bending strap.

Then I glue the purfling in place.

Then I glue the purfling in place.

 

Edge Crest marked

Then I mark the edge of the crest, so I know where to carve the channel.

 

channel complete

Then I carve the channel, using a gouge, and use planes and scrapers to fair-in the curves of the channel and the archings.

 

Arching and purfling complete

Here, the arching and purfling are complete…but the graduations (inside arching) are not begun.

 

Graduation

I begin by measuring the thicknesses all over the plate, so as not to run into any surprises and make the plate too thin. Then I use gouges and planes to bring all the thickness close to what I want. But, to make sure I don’t go too far, I measure and carve out small spots all over, to the exact thickness I want in each little “polka-dot”. That makes a “graduation map” that allows me to follow my plan to completion, by removing all the excess wood between the dots, thus “connecting the dots.”

There are other ways to do this. One involves a special tool, commonly called a “Strad-Spike”, because one was found among the tools of Antonio Stradivari. I have seen them and and have actually used them, but have never gotten around to building one. So…

 

graduation map laid out

Graduation map laid out.

 

Final thicknessing in progress.

Final thicknessing in progress.

 

Graduations almost completed.

Graduations almost completed.

By the way, I think it is interesting to hold the plates up to a lamp and see how much light comes through:

translucent spruce

That is a lot of light coming through that spruce plate…it is about the thinnest plate I have made.

 

translucent maple

Even the maple lets a little light through.

Closing the Corpus

Finally, to install the label and close the corpus. (I always forget to take a picture of the label…sorry.) Most makers put their label in after everything is fully completed. I used to do that, but I found it so frustrating to get a glue-coated label through the f-hole, line it up correctly and get it smoothed out on the back plate…all working through the f-hole…that I decided my labels will go in when I close the corpus; always. That means the label predates the completion by a few weeks at most, as a rule. I think one time there was a long wait,  but that was the lone exception.

Closing the corpus

Closing the corpus

 

Fully glued and clamped, using hot hide glue and spool-clamps.

Fully glued and clamped, using hot hide glue and spool-clamps.

 

Closed corpus from the back.

Closed corpus from the back.

 

Closed corpus from the front.

Closed corpus from the front. Dainty little thing, isn’t it? This is my first 3/4-size violin, and it feels pretty tiny.

 

Finishing

I removed the fingerboard so as to be able to easily access the entire exterior, for final scraping and finishing.

After that, I had a lot of “scraping and looking” to do. (Scrape and look, using a low-angle, dim light, then scrape and look some more.) When everything was as smooth as I could make it, and exactly the shape I wanted, I stained the entire violin with coffee, to get rid of the stark-white bare, new-wood look. It takes at least three coats, usually, to get the color dark enough that it will not shine through the varnish. The collateral effect is that the grain raises because of the water. So, I sand it lightly, to smooth the grain “just enough.” I want the grain to be visible in the final state, but not too visible.

Coffee stain

Coffee stain

 

Then, I rubbed in a coat of the mineral ground. I brush it on liberally, rub it in hard, with my fingers, then wipe it off as hard as I can, using a rag. When it dries, the instrument will be whiter than ever– chalk-white, all over. The first time I did this I was pretty alarmed at the look, but I had just watched Roger Hargrave do the same thing, and knew that the white mineral would completely disappear with the first coat of sealer or varnish. And it did!

Here is the violin with the sealer applied:

sealer front view

With three coats of coffee, and the dark sealer, the wood looks pretty dark. But it will look good under the varnish.

 

The back, with the seal-coat.

The back, with the seal-coat.

 

After that it was a case of applying several coats of golden varnish, then a few coats of red-brown varnish, and a final two coats of the golden stuff.

 

Front varnish nearly complete

Front varnish nearly complete

 

Back varnish nearly complete

Back varnish nearly complete.

 

front with the final coat of varnish.

There is the front with the final coat of varnish.

 

Set-up

Standard set-up, and the violin will be done! That includes the saddle and endpin, as well as re-installing the fingerboard, fitting and installing pegs, a bridge, the nut, the soundpost, tailpiece, and strings. A chinrest completes the instrument.

Bottom of the violin before the endpin

Bottom of the violin before the endpin and saddle were installed.

 

Endpin installed

Endpin installed: saddle is next.

 

Heres the plan: a rounded saddle

Heres the plan: a rounded saddle to prevent “saddle cracks”. They work because there is no sharp corner to act s a stress riser.

 

 footprint of the saddle

There’s the footprint of the saddle: no further shaping is done until I cut out the mortise in the front plate.

 

Traced saddle mortise

I traced the footprint onto the front plate, and began cutting out the mortise.

 

cut out saddle mortise

Then I cut out the mortise using sharp gouges and a small knife. Any nicks in the varnish will be retouched later.

 

The varying thicknesses of the top plate can then be traced onto the saddle itself, and final shaping can begin.

 

Saddle and endpin complete

Saddle and endpin are nearly complete. The saddle will be filed a little more, and the varnish retouch will happen later on.

 

fingerboard and pegs installed.

I reinstalled the fingerboard, and while the glue is drying, I fit and installed the tuning pegs.

 

Fingerboard and pegs complete.

Fingerboard and pegs complete. Notice the nut is also intalled.

 

Completion

Finally the little violin is complete!

 

Front view of completed 3/4-size violin

Front view of completed 3/4-size violin

 

Side view...

Side view…

 

And the back view.

And the back view.

 

finished scroll

Close-up of the scroll

Thanks for looking. Please keep in mind that the Marylhurst Musical Instrument Show will be April 29th and 3oth. If you can make it, I hope to see you there. This little violin will be there for you to test drive, along with others.

 

 

 

 

 

 

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